title: Germline variants in MRE11/RAD50/NBN complex genes in childhood leukemia.
abstract: BACKGROUND
  The MRE11, RAD50, and NBN genes encode proteins of the MRE11-RAD50-NBN (MRN) complex involved in cellular response to DNA damage and the maintenance of genome stability. In our previous study we showed that the germline p.I171V mutation in NBN may be considered as a risk factor in the development of childhood acute lymphoblastic leukemia (ALL) and some specific haplotypes of that gene may be associated with childhood leukemia. These findings raise important questions about the role of mutations in others genes of the MRN complex in childhood leukemia. The aim of this study was to answer the question whether MRE11 and RAD50 alterations may be associated with childhood ALL or AML.
  
  
  METHODS
  We estimated the frequency of constitutional mutations and polymorphisms in selected regions of MRE11, RAD50, and NBN in the group of 220 children diagnosed with childhood leukemias and controls (n=504/2200). The analysis was performed by specific amplification of region of interest by PCR and followed by multi-temperature single-strand conformation polymorphism (PCR-MSSCP) technique. We performed two molecular tests to examine any potential function of the detected the c.551+19G>A SNP in RAD50 gene. To our knowledge, this is the first analysis of the MRE11, RAD50 and NBN genes in childhood leukemia.
  
  
  RESULTS
  The frequency of either the AA genotype or A allele of RAD50_rs17166050 were significantly different in controls compared to leukemia group (ALL+AML) (p<0.0019 and p<0.0019, respectively). The cDNA analysis of AA or GA genotypes carriers has not revealed evidence of splicing abnormality of RAD50 pre-mRNA. We measured the allelic-specific expression of G and A alleles at c.551+19G>A and the statistically significant overexpression of the G allele has been observed. Additionally we confirmed the higher incidence of the p.I171V mutation in the leukemia group (7/220) than among controls (12/2400) (p<0.0001).
  
  
  CONCLUSIONS
  The formerly reported sequence variants in the RAD50 and MRE11 gene may not constitute a risk factor of childhood ALL in Polish population. The RAD50_rs17166050 variant allele is linked to decreased ALL risk (p<0.0009, OR=0.6358 (95%CI: 0.4854-0.8327)). Despite the fact that there is no splicing abnormality in carriers of the variant allele but an excess of the G over the A allele was consistently observed. This data demonstrate that some specific alternations of the RAD50 gene may be associated with childhood ALL.
authors.affiliation: Department of Molecular Pathology, Institute of Human Genetics Polish Academy of Sciences, Strzeszyńska 32, 60-479, Poznań, Poland. m_mosor@man.poznan.pl.
authors.forename: Maria
authors.initials: M
authors.lastname: Mosor
authors.forename: Iwona
authors.initials: I
authors.lastname: Ziółkowska-Suchanek
authors.forename: Karina
authors.initials: K
authors.lastname: Nowicka
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Dzikiewicz-Krawczyk
authors.forename: Danuta
authors.initials: D
authors.lastname: Januszkiewicz-Lewandowska
authors.forename: Jerzy
authors.initials: J
authors.lastname: Nowak
mesh_terms: D017766:Acid Anhydride Hydrolases; D000293:Adolescent; D000483:Alleles; D016022:Case-Control Studies; D018797:Cell Cycle Proteins / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D004260:DNA Repair; D045643:DNA Repair Enzymes / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D005787:Gene Frequency; D042822:Genomic Instability; D005838:Genotype; D018095:Germ-Line Mutation; D006801:Humans; D007223:Infant; D007938:Leukemia / Q000175:diagnosis / Q000235:genetics*; D000076228:MRE11 Homologue Protein; D046912:Multiprotein Complexes / Q000235:genetics; D009687:Nuclear Proteins / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C121766:MRE11 protein, human; D046912:Multiprotein Complexes; C112156:NBN protein, human; D009687:Nuclear Proteins; D000076228:MRE11 Homologue Protein; D017766:Acid Anhydride Hydrolases; C112158:RAD50 protein, human; D045643:DNA Repair Enzymes